Tue, 09 Oct 2012 10:09:34 -0700
7197424: update copyright year to match last edit in jdk8 hotspot repository
Summary: Update copyright year to 2012 for relevant files
Reviewed-by: dholmes, coleenp
1 /*
2 * Copyright (c) 1998, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #include "precompiled.hpp"
26 #include "compiler/compileBroker.hpp"
27 #include "gc_interface/collectedHeap.hpp"
28 #include "memory/resourceArea.hpp"
29 #include "oops/method.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "runtime/interfaceSupport.hpp"
32 #include "runtime/mutexLocker.hpp"
33 #include "runtime/os.hpp"
34 #include "runtime/vmThread.hpp"
35 #include "runtime/vm_operations.hpp"
36 #include "services/runtimeService.hpp"
37 #include "utilities/dtrace.hpp"
38 #include "utilities/events.hpp"
39 #include "utilities/xmlstream.hpp"
40 #ifdef TARGET_OS_FAMILY_linux
41 # include "thread_linux.inline.hpp"
42 #endif
43 #ifdef TARGET_OS_FAMILY_solaris
44 # include "thread_solaris.inline.hpp"
45 #endif
46 #ifdef TARGET_OS_FAMILY_windows
47 # include "thread_windows.inline.hpp"
48 #endif
49 #ifdef TARGET_OS_FAMILY_bsd
50 # include "thread_bsd.inline.hpp"
51 #endif
53 #ifndef USDT2
54 HS_DTRACE_PROBE_DECL3(hotspot, vmops__request, char *, uintptr_t, int);
55 HS_DTRACE_PROBE_DECL3(hotspot, vmops__begin, char *, uintptr_t, int);
56 HS_DTRACE_PROBE_DECL3(hotspot, vmops__end, char *, uintptr_t, int);
57 #endif /* !USDT2 */
59 // Dummy VM operation to act as first element in our circular double-linked list
60 class VM_Dummy: public VM_Operation {
61 VMOp_Type type() const { return VMOp_Dummy; }
62 void doit() {};
63 };
65 VMOperationQueue::VMOperationQueue() {
66 // The queue is a circular doubled-linked list, which always contains
67 // one element (i.e., one element means empty).
68 for(int i = 0; i < nof_priorities; i++) {
69 _queue_length[i] = 0;
70 _queue_counter = 0;
71 _queue[i] = new VM_Dummy();
72 _queue[i]->set_next(_queue[i]);
73 _queue[i]->set_prev(_queue[i]);
74 }
75 _drain_list = NULL;
76 }
79 bool VMOperationQueue::queue_empty(int prio) {
80 // It is empty if there is exactly one element
81 bool empty = (_queue[prio] == _queue[prio]->next());
82 assert( (_queue_length[prio] == 0 && empty) ||
83 (_queue_length[prio] > 0 && !empty), "sanity check");
84 return _queue_length[prio] == 0;
85 }
87 // Inserts an element to the right of the q element
88 void VMOperationQueue::insert(VM_Operation* q, VM_Operation* n) {
89 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check");
90 n->set_prev(q);
91 n->set_next(q->next());
92 q->next()->set_prev(n);
93 q->set_next(n);
94 }
96 void VMOperationQueue::queue_add_front(int prio, VM_Operation *op) {
97 _queue_length[prio]++;
98 insert(_queue[prio]->next(), op);
99 }
101 void VMOperationQueue::queue_add_back(int prio, VM_Operation *op) {
102 _queue_length[prio]++;
103 insert(_queue[prio]->prev(), op);
104 }
107 void VMOperationQueue::unlink(VM_Operation* q) {
108 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check");
109 q->prev()->set_next(q->next());
110 q->next()->set_prev(q->prev());
111 }
113 VM_Operation* VMOperationQueue::queue_remove_front(int prio) {
114 if (queue_empty(prio)) return NULL;
115 assert(_queue_length[prio] >= 0, "sanity check");
116 _queue_length[prio]--;
117 VM_Operation* r = _queue[prio]->next();
118 assert(r != _queue[prio], "cannot remove base element");
119 unlink(r);
120 return r;
121 }
123 VM_Operation* VMOperationQueue::queue_drain(int prio) {
124 if (queue_empty(prio)) return NULL;
125 DEBUG_ONLY(int length = _queue_length[prio];);
126 assert(length >= 0, "sanity check");
127 _queue_length[prio] = 0;
128 VM_Operation* r = _queue[prio]->next();
129 assert(r != _queue[prio], "cannot remove base element");
130 // remove links to base element from head and tail
131 r->set_prev(NULL);
132 _queue[prio]->prev()->set_next(NULL);
133 // restore queue to empty state
134 _queue[prio]->set_next(_queue[prio]);
135 _queue[prio]->set_prev(_queue[prio]);
136 assert(queue_empty(prio), "drain corrupted queue");
137 #ifdef DEBUG
138 int len = 0;
139 VM_Operation* cur;
140 for(cur = r; cur != NULL; cur=cur->next()) len++;
141 assert(len == length, "drain lost some ops");
142 #endif
143 return r;
144 }
146 void VMOperationQueue::queue_oops_do(int queue, OopClosure* f) {
147 VM_Operation* cur = _queue[queue];
148 cur = cur->next();
149 while (cur != _queue[queue]) {
150 cur->oops_do(f);
151 cur = cur->next();
152 }
153 }
155 void VMOperationQueue::drain_list_oops_do(OopClosure* f) {
156 VM_Operation* cur = _drain_list;
157 while (cur != NULL) {
158 cur->oops_do(f);
159 cur = cur->next();
160 }
161 }
163 //-----------------------------------------------------------------
164 // High-level interface
165 bool VMOperationQueue::add(VM_Operation *op) {
167 #ifndef USDT2
168 HS_DTRACE_PROBE3(hotspot, vmops__request, op->name(), strlen(op->name()),
169 op->evaluation_mode());
170 #else /* USDT2 */
171 HOTSPOT_VMOPS_REQUEST(
172 (char *) op->name(), strlen(op->name()),
173 op->evaluation_mode());
174 #endif /* USDT2 */
176 // Encapsulates VM queue policy. Currently, that
177 // only involves putting them on the right list
178 if (op->evaluate_at_safepoint()) {
179 queue_add_back(SafepointPriority, op);
180 return true;
181 }
183 queue_add_back(MediumPriority, op);
184 return true;
185 }
187 VM_Operation* VMOperationQueue::remove_next() {
188 // Assuming VMOperation queue is two-level priority queue. If there are
189 // more than two priorities, we need a different scheduling algorithm.
190 assert(SafepointPriority == 0 && MediumPriority == 1 && nof_priorities == 2,
191 "current algorithm does not work");
193 // simple counter based scheduling to prevent starvation of lower priority
194 // queue. -- see 4390175
195 int high_prio, low_prio;
196 if (_queue_counter++ < 10) {
197 high_prio = SafepointPriority;
198 low_prio = MediumPriority;
199 } else {
200 _queue_counter = 0;
201 high_prio = MediumPriority;
202 low_prio = SafepointPriority;
203 }
205 return queue_remove_front(queue_empty(high_prio) ? low_prio : high_prio);
206 }
208 void VMOperationQueue::oops_do(OopClosure* f) {
209 for(int i = 0; i < nof_priorities; i++) {
210 queue_oops_do(i, f);
211 }
212 drain_list_oops_do(f);
213 }
216 //------------------------------------------------------------------------------------------------------------------
217 // Implementation of VMThread stuff
219 bool VMThread::_should_terminate = false;
220 bool VMThread::_terminated = false;
221 Monitor* VMThread::_terminate_lock = NULL;
222 VMThread* VMThread::_vm_thread = NULL;
223 VM_Operation* VMThread::_cur_vm_operation = NULL;
224 VMOperationQueue* VMThread::_vm_queue = NULL;
225 PerfCounter* VMThread::_perf_accumulated_vm_operation_time = NULL;
228 void VMThread::create() {
229 assert(vm_thread() == NULL, "we can only allocate one VMThread");
230 _vm_thread = new VMThread();
232 // Create VM operation queue
233 _vm_queue = new VMOperationQueue();
234 guarantee(_vm_queue != NULL, "just checking");
236 _terminate_lock = new Monitor(Mutex::safepoint, "VMThread::_terminate_lock", true);
238 if (UsePerfData) {
239 // jvmstat performance counters
240 Thread* THREAD = Thread::current();
241 _perf_accumulated_vm_operation_time =
242 PerfDataManager::create_counter(SUN_THREADS, "vmOperationTime",
243 PerfData::U_Ticks, CHECK);
244 }
245 }
248 VMThread::VMThread() : NamedThread() {
249 set_name("VM Thread");
250 }
252 void VMThread::destroy() {
253 if (_vm_thread != NULL) {
254 delete _vm_thread;
255 _vm_thread = NULL; // VM thread is gone
256 }
257 }
259 void VMThread::run() {
260 assert(this == vm_thread(), "check");
262 this->initialize_thread_local_storage();
263 this->record_stack_base_and_size();
264 // Notify_lock wait checks on active_handles() to rewait in
265 // case of spurious wakeup, it should wait on the last
266 // value set prior to the notify
267 this->set_active_handles(JNIHandleBlock::allocate_block());
269 {
270 MutexLocker ml(Notify_lock);
271 Notify_lock->notify();
272 }
273 // Notify_lock is destroyed by Threads::create_vm()
275 int prio = (VMThreadPriority == -1)
276 ? os::java_to_os_priority[NearMaxPriority]
277 : VMThreadPriority;
278 // Note that I cannot call os::set_priority because it expects Java
279 // priorities and I am *explicitly* using OS priorities so that it's
280 // possible to set the VM thread priority higher than any Java thread.
281 os::set_native_priority( this, prio );
283 // Wait for VM_Operations until termination
284 this->loop();
286 // Note the intention to exit before safepointing.
287 // 6295565 This has the effect of waiting for any large tty
288 // outputs to finish.
289 if (xtty != NULL) {
290 ttyLocker ttyl;
291 xtty->begin_elem("destroy_vm");
292 xtty->stamp();
293 xtty->end_elem();
294 assert(should_terminate(), "termination flag must be set");
295 }
297 // 4526887 let VM thread exit at Safepoint
298 SafepointSynchronize::begin();
300 if (VerifyBeforeExit) {
301 HandleMark hm(VMThread::vm_thread());
302 // Among other things, this ensures that Eden top is correct.
303 Universe::heap()->prepare_for_verify();
304 os::check_heap();
305 // Silent verification so as not to pollute normal output,
306 // unless we really asked for it.
307 Universe::verify(!(PrintGCDetails || Verbose));
308 }
310 CompileBroker::set_should_block();
312 // wait for threads (compiler threads or daemon threads) in the
313 // _thread_in_native state to block.
314 VM_Exit::wait_for_threads_in_native_to_block();
316 // signal other threads that VM process is gone
317 {
318 // Note: we must have the _no_safepoint_check_flag. Mutex::lock() allows
319 // VM thread to enter any lock at Safepoint as long as its _owner is NULL.
320 // If that happens after _terminate_lock->wait() has unset _owner
321 // but before it actually drops the lock and waits, the notification below
322 // may get lost and we will have a hang. To avoid this, we need to use
323 // Mutex::lock_without_safepoint_check().
324 MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag);
325 _terminated = true;
326 _terminate_lock->notify();
327 }
329 // Deletion must be done synchronously by the JNI DestroyJavaVM thread
330 // so that the VMThread deletion completes before the main thread frees
331 // up the CodeHeap.
333 }
336 // Notify the VMThread that the last non-daemon JavaThread has terminated,
337 // and wait until operation is performed.
338 void VMThread::wait_for_vm_thread_exit() {
339 { MutexLocker mu(VMOperationQueue_lock);
340 _should_terminate = true;
341 VMOperationQueue_lock->notify();
342 }
344 // Note: VM thread leaves at Safepoint. We are not stopped by Safepoint
345 // because this thread has been removed from the threads list. But anything
346 // that could get blocked by Safepoint should not be used after this point,
347 // otherwise we will hang, since there is no one can end the safepoint.
349 // Wait until VM thread is terminated
350 // Note: it should be OK to use Terminator_lock here. But this is called
351 // at a very delicate time (VM shutdown) and we are operating in non- VM
352 // thread at Safepoint. It's safer to not share lock with other threads.
353 { MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag);
354 while(!VMThread::is_terminated()) {
355 _terminate_lock->wait(Mutex::_no_safepoint_check_flag);
356 }
357 }
358 }
360 void VMThread::print_on(outputStream* st) const {
361 st->print("\"%s\" ", name());
362 Thread::print_on(st);
363 st->cr();
364 }
366 void VMThread::evaluate_operation(VM_Operation* op) {
367 ResourceMark rm;
369 {
370 PerfTraceTime vm_op_timer(perf_accumulated_vm_operation_time());
371 #ifndef USDT2
372 HS_DTRACE_PROBE3(hotspot, vmops__begin, op->name(), strlen(op->name()),
373 op->evaluation_mode());
374 #else /* USDT2 */
375 HOTSPOT_VMOPS_BEGIN(
376 (char *) op->name(), strlen(op->name()),
377 op->evaluation_mode());
378 #endif /* USDT2 */
379 op->evaluate();
380 #ifndef USDT2
381 HS_DTRACE_PROBE3(hotspot, vmops__end, op->name(), strlen(op->name()),
382 op->evaluation_mode());
383 #else /* USDT2 */
384 HOTSPOT_VMOPS_END(
385 (char *) op->name(), strlen(op->name()),
386 op->evaluation_mode());
387 #endif /* USDT2 */
388 }
390 // Last access of info in _cur_vm_operation!
391 bool c_heap_allocated = op->is_cheap_allocated();
393 // Mark as completed
394 if (!op->evaluate_concurrently()) {
395 op->calling_thread()->increment_vm_operation_completed_count();
396 }
397 // It is unsafe to access the _cur_vm_operation after the 'increment_vm_operation_completed_count' call,
398 // since if it is stack allocated the calling thread might have deallocated
399 if (c_heap_allocated) {
400 delete _cur_vm_operation;
401 }
402 }
405 void VMThread::loop() {
406 assert(_cur_vm_operation == NULL, "no current one should be executing");
408 while(true) {
409 VM_Operation* safepoint_ops = NULL;
410 //
411 // Wait for VM operation
412 //
413 // use no_safepoint_check to get lock without attempting to "sneak"
414 { MutexLockerEx mu_queue(VMOperationQueue_lock,
415 Mutex::_no_safepoint_check_flag);
417 // Look for new operation
418 assert(_cur_vm_operation == NULL, "no current one should be executing");
419 _cur_vm_operation = _vm_queue->remove_next();
421 // Stall time tracking code
422 if (PrintVMQWaitTime && _cur_vm_operation != NULL &&
423 !_cur_vm_operation->evaluate_concurrently()) {
424 long stall = os::javaTimeMillis() - _cur_vm_operation->timestamp();
425 if (stall > 0)
426 tty->print_cr("%s stall: %Ld", _cur_vm_operation->name(), stall);
427 }
429 while (!should_terminate() && _cur_vm_operation == NULL) {
430 // wait with a timeout to guarantee safepoints at regular intervals
431 bool timedout =
432 VMOperationQueue_lock->wait(Mutex::_no_safepoint_check_flag,
433 GuaranteedSafepointInterval);
435 // Support for self destruction
436 if ((SelfDestructTimer != 0) && !is_error_reported() &&
437 (os::elapsedTime() > SelfDestructTimer * 60)) {
438 tty->print_cr("VM self-destructed");
439 exit(-1);
440 }
442 if (timedout && (SafepointALot ||
443 SafepointSynchronize::is_cleanup_needed())) {
444 MutexUnlockerEx mul(VMOperationQueue_lock,
445 Mutex::_no_safepoint_check_flag);
446 // Force a safepoint since we have not had one for at least
447 // 'GuaranteedSafepointInterval' milliseconds. This will run all
448 // the clean-up processing that needs to be done regularly at a
449 // safepoint
450 SafepointSynchronize::begin();
451 #ifdef ASSERT
452 if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();
453 #endif
454 SafepointSynchronize::end();
455 }
456 _cur_vm_operation = _vm_queue->remove_next();
458 // If we are at a safepoint we will evaluate all the operations that
459 // follow that also require a safepoint
460 if (_cur_vm_operation != NULL &&
461 _cur_vm_operation->evaluate_at_safepoint()) {
462 safepoint_ops = _vm_queue->drain_at_safepoint_priority();
463 }
464 }
466 if (should_terminate()) break;
467 } // Release mu_queue_lock
469 //
470 // Execute VM operation
471 //
472 { HandleMark hm(VMThread::vm_thread());
474 EventMark em("Executing VM operation: %s", vm_operation()->name());
475 assert(_cur_vm_operation != NULL, "we should have found an operation to execute");
477 // Give the VM thread an extra quantum. Jobs tend to be bursty and this
478 // helps the VM thread to finish up the job.
479 // FIXME: When this is enabled and there are many threads, this can degrade
480 // performance significantly.
481 if( VMThreadHintNoPreempt )
482 os::hint_no_preempt();
484 // If we are at a safepoint we will evaluate all the operations that
485 // follow that also require a safepoint
486 if (_cur_vm_operation->evaluate_at_safepoint()) {
488 _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned
490 SafepointSynchronize::begin();
491 evaluate_operation(_cur_vm_operation);
492 // now process all queued safepoint ops, iteratively draining
493 // the queue until there are none left
494 do {
495 _cur_vm_operation = safepoint_ops;
496 if (_cur_vm_operation != NULL) {
497 do {
498 // evaluate_operation deletes the op object so we have
499 // to grab the next op now
500 VM_Operation* next = _cur_vm_operation->next();
501 _vm_queue->set_drain_list(next);
502 evaluate_operation(_cur_vm_operation);
503 _cur_vm_operation = next;
504 if (PrintSafepointStatistics) {
505 SafepointSynchronize::inc_vmop_coalesced_count();
506 }
507 } while (_cur_vm_operation != NULL);
508 }
509 // There is a chance that a thread enqueued a safepoint op
510 // since we released the op-queue lock and initiated the safepoint.
511 // So we drain the queue again if there is anything there, as an
512 // optimization to try and reduce the number of safepoints.
513 // As the safepoint synchronizes us with JavaThreads we will see
514 // any enqueue made by a JavaThread, but the peek will not
515 // necessarily detect a concurrent enqueue by a GC thread, but
516 // that simply means the op will wait for the next major cycle of the
517 // VMThread - just as it would if the GC thread lost the race for
518 // the lock.
519 if (_vm_queue->peek_at_safepoint_priority()) {
520 // must hold lock while draining queue
521 MutexLockerEx mu_queue(VMOperationQueue_lock,
522 Mutex::_no_safepoint_check_flag);
523 safepoint_ops = _vm_queue->drain_at_safepoint_priority();
524 } else {
525 safepoint_ops = NULL;
526 }
527 } while(safepoint_ops != NULL);
529 _vm_queue->set_drain_list(NULL);
531 // Complete safepoint synchronization
532 SafepointSynchronize::end();
534 } else { // not a safepoint operation
535 if (TraceLongCompiles) {
536 elapsedTimer t;
537 t.start();
538 evaluate_operation(_cur_vm_operation);
539 t.stop();
540 double secs = t.seconds();
541 if (secs * 1e3 > LongCompileThreshold) {
542 // XXX - _cur_vm_operation should not be accessed after
543 // the completed count has been incremented; the waiting
544 // thread may have already freed this memory.
545 tty->print_cr("vm %s: %3.7f secs]", _cur_vm_operation->name(), secs);
546 }
547 } else {
548 evaluate_operation(_cur_vm_operation);
549 }
551 _cur_vm_operation = NULL;
552 }
553 }
555 //
556 // Notify (potential) waiting Java thread(s) - lock without safepoint
557 // check so that sneaking is not possible
558 { MutexLockerEx mu(VMOperationRequest_lock,
559 Mutex::_no_safepoint_check_flag);
560 VMOperationRequest_lock->notify_all();
561 }
563 //
564 // We want to make sure that we get to a safepoint regularly.
565 //
566 if (SafepointALot || SafepointSynchronize::is_cleanup_needed()) {
567 long interval = SafepointSynchronize::last_non_safepoint_interval();
568 bool max_time_exceeded = GuaranteedSafepointInterval != 0 && (interval > GuaranteedSafepointInterval);
569 if (SafepointALot || max_time_exceeded) {
570 HandleMark hm(VMThread::vm_thread());
571 SafepointSynchronize::begin();
572 SafepointSynchronize::end();
573 }
574 }
575 }
576 }
578 void VMThread::execute(VM_Operation* op) {
579 Thread* t = Thread::current();
581 if (!t->is_VM_thread()) {
582 SkipGCALot sgcalot(t); // avoid re-entrant attempts to gc-a-lot
583 // JavaThread or WatcherThread
584 t->check_for_valid_safepoint_state(true);
586 // New request from Java thread, evaluate prologue
587 if (!op->doit_prologue()) {
588 return; // op was cancelled
589 }
591 // Setup VM_operations for execution
592 op->set_calling_thread(t, Thread::get_priority(t));
594 // It does not make sense to execute the epilogue, if the VM operation object is getting
595 // deallocated by the VM thread.
596 bool concurrent = op->evaluate_concurrently();
597 bool execute_epilog = !op->is_cheap_allocated();
598 assert(!concurrent || op->is_cheap_allocated(), "concurrent => cheap_allocated");
600 // Get ticket number for non-concurrent VM operations
601 int ticket = 0;
602 if (!concurrent) {
603 ticket = t->vm_operation_ticket();
604 }
606 // Add VM operation to list of waiting threads. We are guaranteed not to block while holding the
607 // VMOperationQueue_lock, so we can block without a safepoint check. This allows vm operation requests
608 // to be queued up during a safepoint synchronization.
609 {
610 VMOperationQueue_lock->lock_without_safepoint_check();
611 bool ok = _vm_queue->add(op);
612 op->set_timestamp(os::javaTimeMillis());
613 VMOperationQueue_lock->notify();
614 VMOperationQueue_lock->unlock();
615 // VM_Operation got skipped
616 if (!ok) {
617 assert(concurrent, "can only skip concurrent tasks");
618 if (op->is_cheap_allocated()) delete op;
619 return;
620 }
621 }
623 if (!concurrent) {
624 // Wait for completion of request (non-concurrent)
625 // Note: only a JavaThread triggers the safepoint check when locking
626 MutexLocker mu(VMOperationRequest_lock);
627 while(t->vm_operation_completed_count() < ticket) {
628 VMOperationRequest_lock->wait(!t->is_Java_thread());
629 }
630 }
632 if (execute_epilog) {
633 op->doit_epilogue();
634 }
635 } else {
636 // invoked by VM thread; usually nested VM operation
637 assert(t->is_VM_thread(), "must be a VM thread");
638 VM_Operation* prev_vm_operation = vm_operation();
639 if (prev_vm_operation != NULL) {
640 // Check the VM operation allows nested VM operation. This normally not the case, e.g., the compiler
641 // does not allow nested scavenges or compiles.
642 if (!prev_vm_operation->allow_nested_vm_operations()) {
643 fatal(err_msg("Nested VM operation %s requested by operation %s",
644 op->name(), vm_operation()->name()));
645 }
646 op->set_calling_thread(prev_vm_operation->calling_thread(), prev_vm_operation->priority());
647 }
649 EventMark em("Executing %s VM operation: %s", prev_vm_operation ? "nested" : "", op->name());
651 // Release all internal handles after operation is evaluated
652 HandleMark hm(t);
653 _cur_vm_operation = op;
655 if (op->evaluate_at_safepoint() && !SafepointSynchronize::is_at_safepoint()) {
656 SafepointSynchronize::begin();
657 op->evaluate();
658 SafepointSynchronize::end();
659 } else {
660 op->evaluate();
661 }
663 // Free memory if needed
664 if (op->is_cheap_allocated()) delete op;
666 _cur_vm_operation = prev_vm_operation;
667 }
668 }
671 void VMThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
672 Thread::oops_do(f, cf);
673 _vm_queue->oops_do(f);
674 }
676 //------------------------------------------------------------------------------------------------------------------
677 #ifndef PRODUCT
679 void VMOperationQueue::verify_queue(int prio) {
680 // Check that list is correctly linked
681 int length = _queue_length[prio];
682 VM_Operation *cur = _queue[prio];
683 int i;
685 // Check forward links
686 for(i = 0; i < length; i++) {
687 cur = cur->next();
688 assert(cur != _queue[prio], "list to short (forward)");
689 }
690 assert(cur->next() == _queue[prio], "list to long (forward)");
692 // Check backwards links
693 cur = _queue[prio];
694 for(i = 0; i < length; i++) {
695 cur = cur->prev();
696 assert(cur != _queue[prio], "list to short (backwards)");
697 }
698 assert(cur->prev() == _queue[prio], "list to long (backwards)");
699 }
701 #endif
703 void VMThread::verify() {
704 oops_do(&VerifyOopClosure::verify_oop, NULL);
705 }